Adding Card on Apple Wallet Prompts Bad Phone Number

This question was asked 6 months ago here, 222 people said they had the same issue, but there are no answers.

To start with, I logged into my iCloud account and checked all my emails and my one phone number and they are all correct. Yet when I add a new credit card to Apple Wallet, it wants to authenticate by calling or texting a completely different phone number. In my case, I was affiliated with a person who has that number, so I recognize it, but it's not mine and I don't know why it's showing up to authenticate my credit cards.

Where is that phone number coming from, and how do I change it?